British journal of anaesthesia
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Comparative Study
Predictive pharmacodynamic performance of the Eleveld pharmacokinetic-pharmacodynamic model for propofol: comparison of predicted and measured bispectral index.
The Eleveld pharmacokinetic-pharmacodynamic model for propofol predicts bispectral index (BIS) processed electroencephalogram values from estimated effect-site concentrations. We investigated agreement between measured and predicted BIS values during total intravenous anaesthesia (TIVA). ⋯ BIS predictions by the Eleveld model should be interpreted with caution. In spite of the acceptable MDPE and MDAPE, there are unacceptable degrees of both within-subject and between-subject variation during propofol target-controlled infusions. This limits the use of adjusting targeted concentrations to achieve desired simulated BIS values with confidence.
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Target-controlled infusion (TCI) is a mature technology that enables the delivery of intravenous anaesthetics in the concentration domain. The accuracy of the pharmacologic models used by TCI systems is imperfect, especially regarding pharmacodynamic predictions. ⋯ In this sense, TCI functions as a 'gain switch'. Achieving a steady state is more important than perfect accuracy.
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Ni Eochagain and colleagues report that programmed intermittent bolus and continuous infusion regimens in continuous erector spinae plane (ESP) block catheters produced similar quality of recovery (QoR-15) scores, pain scores, and use of rescue opioids after video-assisted thoracic surgery. This is a reassuring finding for practitioners without access to pumps with programmed intermittent bolus functionality. Nevertheless, it remains plausible that the benefit of one regimen over another might vary depending on the specific infusion parameters. There continues to be scope for research into optimising programmed intermittent bolus delivery and dosing regimens and identifying the most appropriate clinical applications for this mode of infusion.
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Dopaminergic psychostimulants can restore arousal in anaesthetised animals, and dopaminergic signalling contributes to hippocampal-dependent memory formation. We tested the hypothesis that dopaminergic psychostimulants can antagonise the amnestic effects of isoflurane on visuospatial working memory. ⋯ Low-dose isoflurane impairs visuospatial working memory in a nondurable and delay-independent manner that potentially implicates non-hippocampal structures in isoflurane-induced memory deficits. Dopaminergic psychostimulants counteracted sedation but did not reverse memory impairments, suggesting that isoflurane-induced amnesia and isoflurane-induced sedation have distinct underlying mechanisms that can be antagonised independently.